Subsea duplex pump, subsea pumping system, and subsea pumping method

A subsea pump comprising:

• a first chamber;
• a liquid-gas inlet port for receiving liquid and gas into the first chamber;
• a second chamber;
• at least one plunger in the second chamber, the at least one plunger configured to expand outwardly and retract inwardly;
• at least one suction valve communicating the first chamber with the second chamber;
• a gas discharge conduit;
• at least one gas discharge valve communicating the first chamber with the gas discharge conduit;
• and
• at least one liquid discharge port for discharging liquid from the second chamber,
• wherein the at least one plunger retracts inwardly to create a vacuum in the second chamber that opens the at least one suction valve and pulls liquid from the first chamber into the second chamber, and wherein the plunger extends outwardly against the suction to cause the at least one suction valve to close and to create a positive pressure that opens the at least one gas discharge valve and forces the gas that is in the first chamber through the at least one gas discharge valve and into the gas discharge conduit, and
• wherein the liquid in the second chamber is discharged through the at least one liquid discharge port via the positive pressure.